BACKGROUND ON THE INVENTION
1. Field of the Invention
[0001] The present invention relates generally to heating systems, and more particularly
to catalytic heating systems that generate heat and electricity via an oxidation reaction
within a cavity having porous catalytic walls.
2. Description of the Related Art
[0002] The early inventions of liquid fueled heating systems include the oil lamp and the
candle. Each early liquid fueled heating system wicks fuel up to a region where the
fuel could evaporate and combust. Oils and kerosene lanterns can use the wick directly.
Alcohol burners, and in particular methanol burners, need an added thermal conductor
and sleeve tube to the wick in order to deliver enough heat to pre-heat the fuel and
channel vaporized fuel to the burn zone. Without such thermal conductor and sleeve
tube around the alcohol burners, the fuel, the flame front, or plasma burns the associated
wick.
[0003] Recently a need to cleanly burn alcohols rather than other hydrocarbons such as,
for example, oils and kerosene, has arisen. Such alcohols can be derived from waste
materials, also known as "biomass," or manufactured from "alternative energy" sources.
[0004] There are several advantages for burning alcohols rather than hydrocarbons. For example,
methanol burns without smoke, soot and odors. Alcohol fuels, in contrast to kerosene,
burn cooler and can be extinguished with water. Methanol and the alcohols will self
start catalytic combustion on suitable catalysts and produce substantially complete
combustion. Catalytic hydrocarbon burners, on the other hand, generally require a
preheating step for the catalyst. Such advantages in burning alcohols, rather than
hydrocarbons, allow for low cost and fuel effective heaters.
[0005] US 6,358,640 B1 discloses a catalytic heater comprising wherein fuel is supplied through an injector
which draws ambient air into the system. The fuel/air mixture is mixed before it is
catalytically combusted.
[0006] In view of the foregoing, the various exemplary embodiments of the present invention
achieve an efficient combustion heater and heat transfer for space heating. Other
various and similar applications could arise out of the exemplary embodiments of the
present invention as well.
[0007] The mechanism of diffusing fuel and air from separate routes into the fuel, rather
than mixing the air and fuel together and then arriving at the catalyst, results in
a significantly improved combustion situation.
[0008] Conventional burners that mix fuel and air together for combustion within a cavity
can lead to unsteady and explosive burns of the fuel and air. Typically, the larger
the cavity of the conventional burner, the larger the associated explosion. This can
lead to burner fatigue and disastrous results such as, for example, rupture of the
heater.
[0009] It has been found that fuel air mixtures can vary in time which may lead to flame
front loss and explosions when re-establishing the flame. This is a particular problem
in burning of tail gasses from refineries or catalytic reaction systems of two streams
of reactants.
[0010] To avoid such possible disasters, in various exemplary embodiments of the present
invention, fuel and air are separated by a porous catalytic bed. The fuel and air
inter-diffuse to each other through the porous catalytic bed, and ideally there is
no significant non-catalytic cavity filled with an air fuel mixture.
[0011] In the present invention, it has surprisingly been found there is a reduced cost
and operational advantage to having a cavity within the porous catalyst bed, and that
plasma forms within such cavity. The inter-diffusion of fuel and air through the porous
catalytic bed achieves a high occupation time over the catalyst for molecules that
is equal for all molecules present rather than the situation in forced flow through
catalytic beds. In the latter, laminar flow, also known as "streamline flow" or "non-diffusionally
driven," mass flow through a random porous catalytic bed leads to non-uniformity of
gas composition radially in the flow channels, and an uneven flow distribution such
that larger channel flows dominate throughput, and flow rates therein can be high
enough to prevent sufficient diffusion to the catalytic sites to catalytically react
a portion of the fuel and air. Thus, some of the fuel air mixture can pass by the
catalytic surfaces without interacting and produce incomplete combustion. Within the
catalytic bed the inter-diffusion catalytic combustion can achieve a temperature gradient
from highest on the interior cavity and then drops to the outside, important to achieving
complete combustion. The present invention has found that if the outer surfaces of
the catalytic bed are kept below 400°C to 200°C centigrade with a stoichiometric excess
of oxygen to methanol fuel, and a rock wool/catalytic bed is uniformly catalytically
active the unburned combustion products can drop below 1 part in 10,000 or the limits
of our measuring equipment. By depending on this process of inter-diffusion through
a separating catalytic bed wall, the new heater invention does not require fans or
pumps. The new invention may use convection air flow and/or jets to admit fuel vapor
or air in a distributed fashion, leading to a simple, quiet, clean burning and robust
heater system. The hot catalytic surfaces which face the air flow also can fully oxidize
and thereby eliminate gases in the air stream such as hydrocarbons and carbon monoxide
as they flow through the heater. Additional devices that can be coupled with the heater
air inlet are air filters, electrostatic air filters, photo catalytic air filters,
absorbers, adsorbers, scrubbers, similar devices or, for the exhaust air, water condensers
and/or carbon dioxide traps. Scents and perfume emitters arranged with the heater
could be used, and some high molecular weight examples may pass through the heater
unoxidized and so may be borne as an additive to the fuel. This heater system can
also be used in conjunction with a membrane catalytic heater of pending
US Patent Application No. 10/492,018.
SUMMARY
[0012] The present invention includes a catalytic heater comprised of one or more fuel reservoirs,
one or more pipes connected to the one or more reservoirs, one or more porous tubes
connected to the one or more pipes and directed into a cavity, and the cavity bounded
by a porous catalytic wall which is in diffusive contact with an oxidizer gas to achieve
catalytic combustion with fuel from the one or more porous tubes. Oxidation occurs
on the porous catalytic wall between oxidizer molecules diffusing from outside the
porous catalytic wall and a plasma within the cavity diffusing towards the porous
catalytic wall. The plasma is formed from vaporized fuel released via the one or more
porous tubes, such that the oxidation generates heat.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The various exemplary embodiments of the present invention, which will become more
apparent as the description proceeds, are described in the following detailed description
in conjunction with the accompanying drawings, in which:
Fig. 1 is an illustration of a cross sectional view of a jet cavity heater and fueling
system according to an exemplary embodiment of the present invention.
Fig. 2 is an illustration of a cross sectional view of a jet cavity heater having
a flow control valve, capillary tube network, heat pipe, gas products sensor, and
fan according to an exemplary embodiment of the present invention.
Fig. 3 is an illustration of a cross sectional view of the heater system according
to an exemplary embodiment of the present invention, wherein the heater system is
applied a heat pipe or fluid flow system.
Fig. 4 is an illustration of a cross sectional view of catalytic reaction gradients
in a catalytic bed according to an exemplary embodiment of the present invention.
Fig. 5 is an illustration of a cross sectional view of an exemplary embodiment of
heat fuel cells according to the present invention.
Fig. 6 is an illustration of showing a lighting or appliance system according to an
exemplary embodiment of the present invention.
Fig. 7 is an illustration of a close-up cross sectional view of a jet cavity heater
and fueling system having a preheating means according to an exemplary embodiment
of the present invention.
DESCRIPTION OF THE REFERENCED NUMERALS
[0014] In reference to the drawings, similar reference characters denote similar elements
throughout all the drawings. The following is a list of the reference characters and
associated element:
- 1
- catalytic bed cavity
- 2
- catalytic bed
- 3
- porous tube
- 4
- compression fittings
- 5
- boiling fuel
- 6
- one or more small capillary tubes
- 7
- thermal differential expansion actuated relief valve
- 8
- wax actuator
- 9
- valve seal
- 10
- thermal differential expansion actuated thermostat valve
- 11
- wax actuator and valve seat
- 12
- fuel line
- 13
- gravity feed tank
- 14
- fuel level activated switch
- 15
- float
- 16
- rail
- 17
- pressure relief valve vent
- 18
- inlet line
- 19
- outlet line
- 20
- thermopile
- 21
- thermopile electrical outlet
- 22
- heat sink
- 23
- chimney
- 24
- insulating layer
- 26
- electrical diode
- 27
- electrical energy supply
- 28
- peristaltic pump
- 29
- fuel tubing
- 30
- main fuel reservoir
- 31
- fuel
- 32
- fuel inlet and vent cap
- 33
- air flow channels
- 34
- porous tube exit
- 35
- electrical wires
- 36
- fuel filter
- 37
- gas inlet nozzle
- 38
- wax expansion element
- 39
- thermal activated valve
- 40
- gas supply tube
- 41
- small diameter fuel feed tube
- 43
- air inlet
- 77
- battery
- 87
- three-way flow valve
- 88
- first multi flow rate capillary flow limiting tube
- 89
- second multi flow rate capillary flow limiting tube
- 90
- lower heat pipe
- 91
- first side head pipe
- 92
- second side head pipe
- 94
- fan
- 97
- sealed pipe
- 150
- ground level
- 151
- air inlet
- 152
- air vent cover
- 153
- air outlet
- 154
- slab
- 155
- heat pipe
- 159
- heat exchanger wall
- 169
- reservoir of fluid
- 170
- coolant pump
- 171
- fluid flow pipes
- 203
- fluid loops
- 206
- outer stainless steel cage
- 207
- rock wool bed
- 211
- electrical connections
- 213
- wick
- 214
- condensation
- 219
- conductive layer
- 218
- electrically insulating layer
- 220
- copper or aluminum block
- 223
- loops of tubing
- 225
- small diameter pores
- 229
- heat pipe
- 230
- inner stainless steel cage
- 251
- source reservoir
- 253
- air electrode
- 254
- Nafion membrane
- 255
- fuel electrode
- 256
- fuel delivery membrane
- 261
- stainless steel cage
- 262
- cage contact
- 264
- inner surface of catalytic bed
- 272
- heat pipe reservoir
- 274
- fuel independent heat pipe
- 275
- hydrogen gas
- 280
- flow resistance tube
- 284
- heat exchange reservoir
- 285
- valve
- 289
- fuel manifold
- 291
- heat pipe
- 300
- fuel cell
- 301
- check diode
- 302
- capacitor
- 303
- electrical power controller
- 304
- light emitting diode
- 305
- electrical fan
- 306
- television
- 307
- first switch
- 308
- second switch
- 309
- third switch
- 340
- preheating means
DETAILED DESCRIPTION
[0015] Figure 1 is a cross sectional view of a jet cavity heater and fueling system according
to an exemplary embodiment of the present invention. In this exemplary embodiment,
the major components include a catalytic burner, a fuel distribution system, a flow
control system, and a fuel tank system.
[0016] The illustrated catalytic burner has a catalytic bed 2 surrounding a catalytic bed
cavity 1, and a chimney 23. The fuel distribution system is comprised of a porous
tube 3, compression fittings 4, one or more small capillary tubes 6, and a gas inlet
nozzle 37. The flow control system is comprised of a valve seal 9, a wax actuator
and valve seat 11, and a fuel filter 36. The fuel tank system is illustrated as being
comprised of a fuel line 12, a gravity feed tank 13, an inlet line 18, a peristaltic
pump 28, and fuel tubing 29. There may also be one or more electrical wires 35 to
the peristaltic pump 28, thermopile 20, and an electrical energy supply 27, preferably
in the form of a rechargeable battery.
[0017] In an exemplary embodiment, the heater is constructed by forming one or more porous
tubes 3 from sintered powder stainless steel. Although the term, "porous tubes" is
used herein, the tubes only need to have one exit opening. Thus, for the sake of brevity
throughout the detailed description, the term "porous tube" will be used to be interchangeable
with "tube having at least one exit opening" in order to allow for easier understanding.
In a preferred embodiment, these porous jets have an effective average pore diameter
of about 0.5 microns. Other compositions of the one or more porous tubes 3 include,
for example, ceramics, arrangements of metal, glass or ceramic capillary tubes, a
combination thereof. A woven fiber matrix may also be suitable for the one or more
porous tubes.
[0018] It is preferred that the one or more porous tubes 3 have about a 0.3175 cm (0.125
inch) inside diameter and an outside diameter of about 0.635 cm (0.25 inches). In
an exemplary embodiment, the one or more porous tubes 3 are cut to lengths of about
5 cm from an attached fitting connection. Compression fittings 4 are attached to the
one or more porous tubes 3. The compression fittings may be comprised of, for example,
copper or brass.
[0019] In the exemplary example illustrated in Figure 1, there are two porous tubes 3. The
porous tubes 3 and associated plumbing are generally arranged to have fuel enter from
the bottom, and the one or more porous tubes be substantially oriented upward where
the porous tube exits 34 are located. This exemplary orientation is preferable for
holding fuel 31 in the compression fittings 4, small diameter fuel feed tube 41, and
the fuel line 12 until the heater starts vaporizing fuel, and therein substantially
limits the fuel from simply pouring out through the porous tube exits 34.
[0020] The compression fitting 4 in a preferred embodiment have a right angle bend, and
then with an about 0.635 cm (0.25 inch) outer diameter tubing form a substantially
T-shape with another porous tube as shown in Figure 1. The compression fittings 4
and a small diameter fuel feed tube 41 substantially limit flow rate to the one or
more porous tubes, and are connected to a thermal differential expansion actuated
relief valve 7, a wax actuator, and a valve seal 9. The thermal differential expansion
actuated relief valve is preferably mounted on a perimeter frame of the catalytic
heater. Such mounting provides sufficient heat transfer from the catalytic heater
to the thermal differential expansion actuated relief valve to allow the thermal differential
expansion actuated relief valve to open from the heating of the catalytic bed 2 and
use the heat transfer into boiling fuel 5 to keep the thermal differential expansion
actuated relief valve open. It is preferred that the thermal differential expansion
actuated relief valve is a thermal expansion valve that opens at about 63°C and closes
at about 46°C with a wax actuator 8 that moves off the valve seat 9.
[0021] A starting heater fuel delivery system may be formed with an about 0.0254 cm (0.010
inch) inside diameter 0.15875 cm (0.0625 inch) outside diameter and the one or more
small capillary tubes 6 that are placed against an inside bottom surface of the catalytic
bed 2. Such capillary steel tubes may be formed from stainless steel. Catalytic beds
can be comprised of platinum and other catalytic materials dispersed over ceramic
fiber or rock wool bed. Several alumina spheres, coated with 1% platinum by weight,
may be dispersed throughout the catalytic bed to achieve hot spot starting. The one
or more small capillary tubes 6 are connected to the fuel line 12. The one or more
small capillary tube 6 can have limited flow rates determined by laminar flow drag
through one or more small capillary tubes, and by the pressure of the fuel 31 into
the one or more small capillary tubes 6. The flow resistance through the one or more
small capillary tubes 6, small diameter fuel feed tube 41, fuel line 12, and outlet
line 19 can also create an upper power limit on the heater system depending on the
pressure from the gravity feed tank 13. If the temperature in the one or more small
capillary tubes 6 and/or the small diameter fuel feed tube 41 exceeds the boiling
point of the fuel 31, and the fuel boils, the fueling rate dramatically drops to roughly
about five percent of the fuel delivery rate due to the boiling fuel 5 having a considerably
higher volume and flow velocity and therein changing the drag effect through the one
or more capillary tubes.
[0022] A mathematical relationship of the delivered laminar fuel (fluid) flow rate to the
to a pressure of a fuel across a particular tube (P), a radius of the particular tube
(r), a length of the particular tube (l), a viscosity of the particular fuel (µ),
and the density of the fluid (p) is the following:
[0023] This laminar flow resistance mechanism can be used as a self temperature limiting
effect on the heater such that when the fuel boils in the one or more small capillary
tubes 6 and the small diameter fuel feed tube 41, the fuel flow rate will drop by
a factor of roughly 20 and the heater will self limit. This effect is due to the volume
of the liquid fuel changing from about .79 gm/ml to about 0.00114 gm/ml at about 65°C
at sea level air pressure. This results in a volume change of 693 times lower. The
viscosity of the fuel changes from µ(liquid) of about 0.00403 Poise of the liquid
to µ(gas) of about 0.000135 Poise of methanol gas at 65°C. Thus, the fuel delivery
rate is estimated to drop by a factor of 1/23.2 times for gas flow divided by the
fuel delivery rate of liquid fuel. Fuel delivery ratio = Gas fuel delivery/Liquid
fuel delivery = ρ(gas)
∗µ(liquid)/(ρ(liquid)
∗µ(gas))=0.04308=1/23.2.
[0024] In the one or more porous tubes 3 the fuel 31 can flow through small wall pores of
the one or more porous tubes with a flow rate that can be mathematically modeled by
multiplying the number of equivalent small pores by the fuel delivery rate and the
pressure head created by the height of the fuel in the one or more porous tubes. When
the fuel is fully or substantially vaporized, the fuel flow through the small pores
is dramatically reduced and the flow is dominated by the flow through the porous tube
exit 34.
[0025] Essentially the flow through the one or more porous tubes is then dominated by a
jet flow out of the porous tube exit 34 while some flow and diffusion of fuel comes
out through small wall pores of the one or more porous tubes 3. Such jet flow may
be throttled or adjustable as needed. The flow of fuel through the small wall pores
can be catalytically or plasma combusted or reformed on the side of the one or more
porous tubes 3, therein keeping the one or more porous tubes heated to transfer heat
into the fuel to maintain the fuel boiling and vapor flow by supplying the heat of
vaporization of the fuel 31. Although the porous tube exit is illustrated in the figures
as being open, the porous tube may be substantially covered or capped such that the
flow of fuel must escape through the small wall pores and not through the porous tube
exit. In addition, although the porous tubes are illustrated as being in a substantially
vertical direction, the porous tubes may be positioned as being substantially horizontal
relative to a base of the heater or any position between the substantially vertical
and substantially horizontal position. As a result, the sides of the one or more porous
tubes may be covered in a plasma when air (oxygen) is at stoichiometric excess, or
hot plasma, and may also maintain the flame/plasma as the vaporized fuel flows out
of the porous tube exit. A dynamic equilibrium can be achieved on the one or more
porous tubes 3 between small walls pore flow through the sides of the one or more
porous tubes combusting and transferring the heat to provide the heat to vaporize
and possibly reform the fuel in the porous tube exit fuel flow.
[0026] The rate of fuel flow and diffusion through the sides of the one or more porous tubes
3 should automatically adjust to keep the fuel flow through the one or more porous
tubes 3 as a vaporized fuel. If fuel is not vaporized in the one or more porous tubes,
the liquid fuel on an inner surface of the one or more porous tubes 3 will flow and
diffuse through the sides of the one or more porous tubes 3 and increase the heating
of the one or more porous tubes until the porous tube exit is vaporizing more of the
fuel 31, and vice versa. If the fuel is substantially vaporized when the fuel reaches
the one or more porous tubes 3, the fuel flow rate through the sides of the one or
more porous tubes will be reduced and the heating and vaporization of the fuel until
liquid fuel contact returns to a base of the one or more porous tubes 3.
[0027] A similar dynamic equilibrium system can be achieved with the one or more porous
tubes 3 surrounding a vertical wicking arrangement of fuel being wicked into a combustion
area at the porous tube exit 34 and the some of the heat of combustion from a surface
of the one or more porous tubes are transferred into the boiling of the fuel. If the
fuel is fully vaporized within such wick, less fuel is delivered through the sides
of the one or more porous tubes and the delivery of fuel is throttled back. If more
liquid fuel is wicked, the heating of the one or more porous tubes is increased and
the vaporization of the fuel is increased. The preheating means may be, for example,
a catalytic or electric heater.
[0028] For very high flow rates through the one or more porous tubes 3, heat transfer back
to the liquid fuel to vaporize the liquid fuel is needed to maintain the vaporization
of the fuel. In exemplary embodiments herein, preheating through the sides of the
one or more porous tubes 3 is dependent upon liquid or vapor in a closed thermal loop
to achieve maximum responsiveness and thereby create a responsive and dynamic self
fuel vaporizing preheating system. Fig. 7 illustrates a preheating means 340 positioned
adjacent to fuel line 12. Such preheating allows an initial amount of fuel to be heated
without a steady flow of fuel, thereby allowing for more efficient warming of the
heater and with less loss of fuel.
[0029] The preheating means is that through which the liquid fuel passes and in which it
is boiled. Examples of the preheating means include a simple metal tube to a sophisticated
radiator like design. The specifics of how it is designed will be based upon factors
such as the watt output of the desired preheating means, the rate at which the fuel
travels through the heat exchanger, the efficiency at which the specific design can
transfer that heat to the fuel, the temperature of the fuel, the boiling point of
the fuel, etc. The preheating means could also be in close proximity to, or potentially
even attached to, a primary heater cage which could allow the main heater to "take
over" the fuel preheating once the main heater is up to a desired or predetermined
temperature.
[0030] The preheating means is preferably limited in its heat output. This can be accomplished
via fuel restrictions to the preheating means or via some means of thermostatically
controller, such as, for example, with a valve similar to the thermal valve or via
some electrical means, for example, from a simple bimetal thermostat to a computer
(micro-controller) with temperature inputs which operates a valve, or even through
a tube to fuel the preheating means which goes through or near the preheating means
just as the heat exchanger does which causes the fuel flow to dramatically decrease
due to back pressure in the line when the preheating means fuel boils.
[0031] In the catalytic bed cavity 1, the fuel may combust with air at high temperatures
and then diffuse into the adjacent catalytic bed 2 to substantially complete combustion
at lower temperatures in the catalytic bed 2 as the fuel diffusion in the catalytic
bed cavity 1 meets the diffusion of oxygen from the air in the chimney 23.
[0032] The lower temperature catalytic combustion is more complete and favors the products
of carbon dioxide and water versus carbon monoxide and hydrogen which can be produced
in high temperature combustion. The temperature gradient created from the heat transfer
from highest on the inside of the catalytic bed cavity 1 to an outside surface of
the catalytic bed 2 produces the desired temperature gradient for complete combustion
of the fuel and air. Measurements of embodiments of the present the catalytic heater
produced combustion efficiencies of better than 99.984% efficiency in combusting methanol,
as the fuel, with air.
[0033] It should be mentioned that this type of combustion can be used to safely combust
a variety of fuels. An example is that of non-combustible mixtures of gas such as
tail gasses from refineries. Such fuels can be substituted for the liquid fuel and/or
mixed with or in a parallel fueling arrangement feeding the catalytic bed cavity.
Methanol, dimethylether, or liquid fueled porous jets, for example, can be feeding
fuel adjacent to gas inlet nozzle 37 that delivers fuel as a pre-heated gas stream
once the temperatures are high enough to open the wax expansion element 38 and thermal
activated valve 39.
[0034] Catalytically combustible gases such as, for example, hydrogen, carbon monoxide,
methane, propane, pentane, ether, ethane, butane, ethanol, propanol, and other hydrocarbon
compounds may also be used. An example of a gas that can be fed in a refinery tail
gas is a gas that is comprised of some hydrogen and methane and carbon monoxide but
is diluted with sufficient nitrogen and non-combustible gasses such that the gas alone
cannot sustain a flame.
[0035] The pre-heated gas stream in the gas supply tube 40 may be heated from heat transfer
from the chimney 23, the catalytic bed 2, and the exhaust air flow channels 33 into
the gas supply tube 40 and the catalytic bed 2, thereby catalytically oxidizes lean
mixtures of fuel in the catalytic bed 2 with oxygen diffusing through the catalytic
bed 2. A particular advantage of having the fuel pre-heated in the gas supply tube,
separate from the air flow channels 33 and air inlet 43, substantially avoids having
a large volume of mixed fuel air of as in a conventional burner, which can lead to
explosions injuring individuals and property.
[0036] In an exemplary embodiment, the air can also be pre-heated through the heat exchange
with heat transferred from the chimney 23 into the air inlet 43. By pre-heating the
fuel and air, the heater is more efficient. Further, for low combustibility mixtures
in the gas supply tube 40, it may be necessary to maintain combustion because the
energy in the fuel air mixture is insufficient to heat the gas to the combustion temperature
and/or catalytic combustion temperatures.
[0037] In the exemplary embodiment using tail gas, the combustibility of the mixture can
vary in time as the chemical concentrations and temperatures change. Such variances
can lead to unstable combustion and explosions. The thermostatic aspects of exemplary
embodiments of the present heater substantially maintain operational conditions in
the heater; essentially compensating for the varying combustibility of tail gasses.
A catalytic oxidation termination on the cooler outer surface of the catalytic bed
2 with a comparably oxygen-rich environment in the air flow channels 33 substantially
ensures that the catalytic oxidation favors full oxidation of the carbon monoxide
and hydrogen in the gasses.
[0038] Exhaust of from the catalytic heater diffuses out into the convective or forced air
flow past the catalytic bed 2. The catalytic bed 2 radiates to the surrounding chimney
23. Conduction, convection, and radiant heat transfer will occur from the catalytic
bed 2. Additional heat transfer could occur by conduction contact to the catalytic
bed 2 or conduction from the chimney 23. Heat pipes and circulated fluid conductors
can be placed on the catalytic bed 2 or chimney 23. For example, one or more thermopiles
20 are placed in thermal contact on the chimney 23 or in radiant thermal contact with
the catalytic bed 2. The thermopile is preferably electrically insulated through an
insulating layer while still making thermal contact. Such insulating layers are preferably
comprised of alumina. The heat sink 22, also known as a cold junction, of the thermopile
can be arranged to pre-heat air in the air inlet 43. The heat sink 22 is also cooled
by convecting air into surrounding air. The low temperature heat sinking 22 of the
heater can be incorporated into structures such as floor mats, walls, beds, automobiles,
machinery, electronics, and apparel drying racks.
[0039] Fuel delivery to the small diameter fuel feed tubes 41 and the one or more porous
tubes 3 is from a gravity feed tank 13 and main fuel reservoir 30. The main fuel reservoir
30 may have a fuel inlet and vent cap 32. Fuel is directed from the main fuel reservoir
30 to the gravity feed tank via the pump 28, the fuel tubing 29, and the inlet line
18. The gravity feed tank may include a pressure relief valve vent 17. From the gravity
fuel tank, the fuel goes though a piping system and series of flow control components
including an outlet line 19, the fuel filter 36, the thermal differential expansion
actuated thermostat valve 10, the wax actuator and fuel seat 11, the thermal differential
expansion actuated relief valve 7, the wax actuator 8, and the valve seat 9.
[0040] The main fuel reservoir 30 may be a fuel tank such as, for example, a 50 gallon tank
that can be located outside the building to be heated. Such tank can be buried, covered,
and the like for aesthetic desires. The fuel inlet and vent cap 32 substantially prevents
excessive negative or positive pressure buildup within the main fuel reservoir.
[0041] The pump 28 may be in the form of, for example, a peristaltic pump or a piezoelectric
pump diaphragm pump. Electrical power is delivered to the pump through electrical
wires 35.
[0042] The gravity feed tank 13 of exemplary embodiments may be of approximately 300 ml
fuel volume to provide a steady gravity pressure head feed to the heater. Although
described herein as a gravity feed tank, fuel may flow through the present system
by pressure and/or pump action. Within the gravity feed tank 13 there may be a fuel
level activated switch 14 located on a float 15 and rail 16. This fuel level activated
switch turns on the fuel pump 28 in the main fuel reservoir 31 when the fuel level
is determined to be low, and turns off when the fuel level is determined to be at
the desired level or too high. The gravity feed tank 13 has a pressure relief valve
vent 17 to substantially regulate the pressure inside the gravity feed tank and avoid
positive or negative pressure build up and thereby allow this tank to deliver a precise
gravity head pressure to the heater. The pressure relief valve vent 17 could be incorporated
in an access cap to the gravity feed tank 13.
[0043] In a starting mode of operation the heater system can be started by filling the gravity
feed tank 13 with fuel. This could fuel the heater and be able to generate sufficient
electricity delivered to the thermopile electrical outlet 21 through an electrical
diode 26 from the thermopile 20 to run the pump 28 in the main fuel reservoir 30 or
charge the electrical energy supply 27 in the form of one or more batteries which
may then run the pump 28 in the main fuel reservoir 30.
[0044] The fuel filter 36 may be, for example, a porous stainless steel frit with average
10 micron pores positioned in the outlet line 19 with a stainless steel holder.
[0045] The thermal differential expansion actuated thermostat valve 10 and wax actuator
and valve seat 11 open to allow fuel to flow below a predetermined temperature, and
then and close to stop or slow fuel to flow above a predetermined temperature. In
a variation, only one of the thermal differential expansion actuated thermostat valve
10 and wax actuator and valve seat 11 open, thereby stopping or slowing the flow of
fuel. The predetermined temperature can be set with a screw dial adjustment to the
wax actuator and valve seat 11 force against the thermal differential expansion actuated
thermostat valve 10. Other types of thermostat valves such as electrically actuated
valves or electrically driven pumps could also be used for the thermal differential
expansion actuated thermostat valve.
[0046] The heater system may also include sensors such as carbon monoxide or oxygen content
sensors, fans, and lights, and the like.
[0047] In operation, a side of the thermopile 22 adjacent to the chimney 23 is heated wherein
the heat is then transferred to the other side of the thermopile 22 and into the heat
sink 22 which is cooled by air flowing in the air inlet. Electrical current generated
by the thermopile goes through the thermopile electrical outlet 21, through an electrical
diode 26 to charge a battery, the electrical energy supply 27. The electrical diode
26 is necessary to ensure one-way electrical current charging of the battery and not
allow the battery to be discharged back through the thermopile 20 when the heater
is off. It should be noted that a super capacitor could be used to store the electrical
energy rather than a battery. The battery may be in the form of, for example, a nickel
metal hydride battery, a lead acid battery, a lithium polymer battery, or a lithium
ion battery. The stored electrical energy in the battery will flow when the fuel level
activated switch 14 closes when the fuel level is low. The electrical current flows
through the pump 28 and more fuel 31 is pumped into the gravity feed tank 13. When
the fuel in the gravity feed tank reaches a predetermined level, the fuel level activated
switch opens and the electrical current to the pump 28 is stopped. It may be useful
in some situations to have a check valve in the inlet line 18 such that when the pump
28 stops pumping it does not siphon back through the fuel line 29 into the main fuel
reservoir 30.
[0048] Fuel may also be pumped using a manual and/or automatic pump in order to advance
an initial amount of fuel to be preheated such that the heater may more efficiently
reach a desired temperature without a steady flow of fuel.
[0049] In Figure 2 the heater system is shown with additional embodiments of a first and
second multi flow rate capillary flow limiting tubes 88 and 89, respectively, having
a three-way flow valve 87, a lower heat pipe 90, a first and second side head pipe
91 and 92, respectively, on the electrical insulation layer between the theromopile
and chimney 23, a fan 94, air flow and a combustion electronic sensor.
[0050] In this exemplary embodiment, the flow control through the valve and capillary tubes
allows the power output of the heater to be set by different flow rates through the
first and second multi flow rate capillary flow limiting tubes 88 and 89. The first
and second multi flow rate capillary tubes can also be placed as a safety feature
with a thermal contact to the catalytic heater such that if the heater is excessively
hot, such as, for example, when air flow is blocked in the chimney, the fuel in the
first and second multi flow rate capillary tubes will boil and limit the fuel delivery
to the heater. In such exemplary embodiment, electrical insulation layer between the
theromopile and chimney 23 is used in conjunction with a lower heat pipe 90, a first
and second side head pipe 91 and 92, and the heat sink 22, which may be in the form
of a finned heat sink. The output of the thermopile is used to run the air flow fan
94, pumps 28, and charge batteries 77. The first and second multi flow rate capillary
flow limiting tubes may be positioned on a surface of the chimney 23, or on the surface
of the heat sink 22.
[0051] In the exemplary embodiment illustrated in Figure 2, the more porous tubes 3 are
comprised of sintered powder stainless steel having an effective average pore diameter
of 0.5 microns. The porous tubes preferably have a 0.3175 cm (0.125 inch) inside diameter
and an outside diameter of 0.635 cm (0.25 inches), and are cut to lengths of five
cm from the compression fittings 4, preferably comprised of brass. The compression
fitting preferably have a right angle bend and then 0.635 cm (0.25 inch) outer diameter
tubing to form a T-shape with another porous tube as shown in Figure 2. The small
diameter fuel feed tube 41 may be brazed as 0.635 cm (1/4 inch) diameter copper tube
from 0.3175 cm (1/8 inch) diameter tubing. The small diameter fuel feed tube capillary
tubes limit the flow rate to the jets and are connected to a valve seal 9 that is
mounted on the perimeter frame of the catalytic bed 2 or chimney 23 of the catalytic
heater. Such mounting to the catalytic bed 2 or chimney 23 and thermal conductivity
of the porous tubes and small diameter fuel feed line provides sufficient heat transfer
from the heater to the thermal differential expansion actuated relief valve 7 to allow
such valve to open from the heating of the catalytic bed and use the heat transfer
into the boiling fuel to keep the thermal differential expansion actuated relief valve
open.
[0052] Exhaust from the catalytic heater diffuses out into the convective or forced air
flow past the catalytic bed 2. The catalytic bed 2 radiates to the surrounding chimney
23. Conduction, convection, and radiant heat transfer will occur from the catalytic
bed 2. Additional heat transfer could occur by conduction contact to the catalytic
bed 2 or conduction from the chimney 23. In an example embodiment, heat is transferred
to the wall of the chimney 23 and heat travels through the thermopile. The thermopile
is then heat sinked through the lower heat pipe 90 and the first and second side head
pipe 91 and 92 which dissipate heat through a heat sink 22 to the surrounding air
or surfaces such a floor mat, apparel, furniture, ducts, machinery, automobiles, mirrors,
windows, electronics, or building walls.
[0053] The lower heat pipe 90 and the first and second side head pipe 91 and 92 may include
of a working fluid in a sealed pipe 97, which may be in the form of a flexible walled
heat pipe, with a wicking material on an inside of the sealed pipe 97. Gravity flow
back is used to return condensed working fluid back to the wicking material. If an
impurity is added to the heat pipe working fluid or pressurization of the sealed pipe
97 is used, the boiling point of the working fluid could be set and the sealed pipe
could remove heat and deliver heat at a set temperature.
[0054] The three-way flow valve 87 is positioned after the fuel filter 36 in the embodiment
illustrated in Figure 2. Typical positions of the three-way valve valve 87 are: off,
and two flow routes to the different flow rate capillary tubes.
[0055] The electrical system for exemplary embodiments of the present invention may include
a thermopile generator, diode, one or more batteries, a fuel level switch, fuel pump,
air flow fan, and a combustion sensor in the exhaust air stream. The combustion sensor
may detect such gases as, for example, carbon monoxide, unburned fuel, heat, or oxygen
content. If oxygen content of the system goes too low, or if carbon monoxide or unburned
fuel is too high, the combustion sensor can shut off power to the fuel pump and shut
down the heater system. Other possible arrangements are to shut off the fuel valve
and sound an alert, a light or visual display of the fault condition to the user.
The combustion sensor could also detect heat and regulate power of the heater by controlling
the fuel delivery valve to regulate the temperature or heat delivery to the room,
apparel, machinery. The air flow fan moves air past the heater system to increase
air flow through the chimney 23 and increase oxygen delivery to the catalytic bed
and therein increase the heat transfer to the surroundings.
[0056] The heater could be started by pouring fuel into the gravity feed tank 13 through
the port capped with a vent. The fuel is gravity fed through the filter, then the
through the three-way flow valve 87 and one the first and second multi flow rate capillary
flow limiting tubes 88 and 89. The fuel flows into the one or more small capillary
tubes 6. The fuel, wicks into the catalytic bed where it is vaporized, diffuses, and
catalytically combusts in the catalytic bed with the in-diffusion of oxygen from the
outside air. Heat from the catalytic combustion increases the temperature of the porous
tubes, the seal pipe, one or more small capillary tubes, the porous tubes, and the
thermal differential expansion actuated relief valve. When the temperature reaches
a temperature that opens the thermal differential expansion actuated relief valve,
such valve opens and a larger flow rate of fuel goes to the porous tubes. Some of
the fuel vaporizes in the porous tubes and a portion of the fuel diffuses through
the sides of the porous tubes. Increased catalytic combustion occurs in the catalytic
bed as more diffusion of fuel meets oxygen diffusion in the catalytic bed until the
heater self temperature regulates through the thermal differential expansion actuated
thermostat valve. When steady state operation of the heater is achieved, the temperature
is highest in an interior of the catalytic bed and cooler on an outside of the catalytic
bed due to removal of heat from the outside by radiation, conduction, and convection.
By being coolest on the exterior, the catalytic bed lowest equilibrium temperature
favors complete combustion, thereby minimizing carbon monoxide formation on the exterior
of the catalytic bed.
[0057] Plasma can also form within the catalytic bed cavity of the catalytic bed. This plasma
can also heat the porous tubes and connected fuel lines to keep the fuel vaporized
in a dynamic equilibrium to maintain a steady jet of vaporized fuel to the catalytic
bed cavity within the catalytic bed. Such dynamic equilibrium is a balance of the
heating the porous tubes to vaporize the fuel, and to supply fuel through the sides
of the porous tubes to heat the sides of the porous tubes. When the porous tubes are
hot, fuel is vaporized and less fuel is delivered through the sides of the porous
tubes reducing the heating of the porous tubes. When the porous tubes are cool, more
fuel is delivered through the sides of the porous tubes and the fuel delivery through
the sides of the porous tubes is increased.
[0058] In operation the heater creates a high temperature difference across the thermopile
to produce electrical current to charge the battery, run the fuel pump in the main
fuel reserve, run the sensor system and run the air flow fan. A heat pipe system including,
for example, the lower heat pipe 90 and the first and second side head pipe 91 and
92 can be extended away from the heater to do tasks such as heat machinery, fuel cells,
beds, apparel, floors, walls of buildings.
[0059] Figure 3 illustrates an exemplary embodiment having the catalytic bed thermally connected
to a heat pipe or fluid flow system. In this particular embodiment, the heaters bellow
the height of the intended condensation area or heat delivery area, thereby allowing
convection and condensation to cycle the fluids and the air flow through the catalytic
heaters and pipes.
[0060] In Figure 3 the ground level 150 is shown and the air inlet 151 come up out of the
ground. An air vent cover or roof 152 is used to prevent rain, snow, dirt, and the
like from falling down into the heater system. The air vent cover may also act as
a diverter to prevent the outlet exhaust air from mixing with the inlet air stream.
[0061] Air enters the air vent 151 and flows down into the heater system. As the air flows,
it is heated through the heat exchanger wall 159 separating the air inlet and air
outlet 153. This heat exchange from the exhaust air into the inlet air allows the
heater to be more efficient by recovering heat from the exhaust. However, condensation
of water in the exhaust air can occur which is important in runway heating applications
to reduce the condensation plume and avoid obscuration of the runway. Condensed water
on the heat exchanger wall can be collected and removed from the system. When the
air reaches the catalytic heater bed, it diffuses into the catalytic bed and catalytic
bed cavity. Plasma combustion can occur inside the catalytic bed cavity and then catalytic
combustion can occur in the catalytic bed at a relatively lower temperature. The exterior
of the catalytic bed is in conduction, radiation, and convective thermal contact with
the air inlet and the heat pipes or fluid flow pipes 171. This insures that there
is a temperature gradient from the inside to the outside of the catalytic bed. Such
gradient of temperature in the catalytic bed, diffusion of reactants, and excess oxygen
supply on the exterior surface of the catalytic bed assures that the heater achieves
substantially complete combustion.
[0062] If the heater is operated with excessive fuel or likewise insufficient air flow,
the heater will produce non-combusted fuel in the exhaust and can be detected with
a catalytic sensor in the exhaust ash shown in Figure 2 the fuel pumps can then be
throttled or shut down. Through conduction, convection, and radiant heat transfer
with the fluid flow tubes, the fluid boils or is flowed by the heater. When boiling
of the fluid is not occurring, a pump 28 can be used to circulate the fluid. A reservoir
of fluid 169 is used to allow the system to hold all the fluid in the pipes of the
system allowing for the fluid circulation to be stopped. Thus the reservoir of fluid
169 and pump 28 can act as an on-off mechanism for the heat pipe 155. The reservoir
of fluid 169 may also be used to simply be able to allow the pipes to be empty to
repair the pipes.
[0063] It is anticipated that in working situations wherein the pipes are embedded in a
runway, road way, or concrete slab of a building, leaks could occur. The heat pipe
operation would be hampered by leaks by allowing air into the pipes, but the system
could still be operated by circulating liquid or a mixture of liquid and gas vapor
using the coolant pump 170. The reservoir of fluid 169 could be sized sufficiently
to permit a modest leakage rate and serviceable refilling of the fluid circulation
system. The working fluid in the piping desirably is an inert low cost fluid with
a high thermal capacity, does not freeze, and boils at the temperature that the heater
needs to deliver sufficient heat to the surface of the runway, landing pad, roadway,
walk way, athletic fields, greenhouse, building floor, ship deck, automobile, machinery,
or structure. Examples of such fluids include, for example, as chlorofluorocarbon
fluids, ammonia, water, methanol, ethanol, carbon dioxide.
[0064] Particular applications such as a concrete slab 154 may need temperatures above the
thermal reservoir of the ground so the heater is turned on and increases the working
fluid temperatures above the heater to achieve higher heat flow rates into the slab
154. The thermal reservoir could be the ground 150, a body of working fluid, or a
body of water, which is heated by a heat source of solar energy, geothermal energy,
or waste heat from heat pipe systems, or waste heat off a thermal power plant. The
thermal reservoir of fluid 169 could be in thermal contact with the heat source through
circulated fluid filled pipes from the heat source and used to store thermal energy
in the working fluid reservoir of fluid 169 and ground 150.
[0065] In Figure 4 an exemplary embodiment of the heater system is shown coupled to a heat
pipe and a fluid flow heat transfer system. The heater system is constructed with
the porous tubes substantially surrounded by the catalytic bed cavity of the catalytic
bed 2. The catalytic bed may be used as preheating means for heating an initial amount
of fuel without a steady flow of fuel. The catalytic bed cavity preferably has an
inner stainless steel cage 230 and an outer stainless steel cage 206 that is comprised
of porous catalytically coated rock wool bed 207 and catalyst coated alumina spheres
232 embedded in the porous catalytically coated rock wool bed 207. The term "cage"
as used throughout is meant to convey a surrounding means that has at least some portion
that is open, perforated, vented, or the like. The porous tubes have small diameter
pores 225 on the side of the jet nozzle the allow a low rate of fuel delivery through
the sides of the tube to maintain heating of the nozzle to maintain the boiling of
the liquid fuel and jet flow out the end of the porous tube exit. The moderated heating
rate of the fuel to achieve a steady jet flow rate is maintained by the dynamic equilibrium
between liquid and gaseous fueling rate differences through the small diameter pores
225 of the porous tube exit.
[0066] The air flow in this embodiment is flowing past the catalytic heater bed in the chimney
surrounding the catalytic bed. The heat from the catalytic bed 2 can be transferred
to air or fluids outside of the heater and chimney through one or more heat pipes
or a fluid pumped or valve circulated system. The pumped or valved fluid circulation
system could circulate a liquid, boiling liquids, and gasses. A passive heat pipe
system shown makes thermal contact through a copper or aluminum block 220 to the inner
stainless steal cage 230 and by radiant heat transfer from the catalytic bed cavity
1 inside the catalytic bed. In such arrangement, the thermal contact is with catalytic
bed cavity to achieve the highest possible temperature difference across the thermopile.
Due to properties of the diffusion nature of this catalytic bed, the oxygen diffusing
in on the surface of the catalytic bed is heated while oxygen diffusing out as exhaust
products from the inside of the catalytic bed are cooling, the higher temperatures
of the heater will be where the inter-diffusion of reactants meet to achieve combustion
and or catalytic combustion. By thermostatically controlling the fuel delivery a maximum
temperature zone in the catalytic bed and plasma in the catalytic bed cavity can be
arranged to be near where the stainless steel cage can collect the heat and deliver
it to the copper block 220 and thermopile for maximum efficiency.
[0067] In steady state operation, the combustion zone can be stationary within the catalytic
bed and the heat losses by conduction and radiation through the catalytic bed can
be kept small compared to the heat delivered through the stainless steel cage 230.
This is in contrast to a flowing combustion system where heat is removed by the hot
gas flowing over a metal surfaces and subsequent lower temperature heat removed further
along the flow. In the flowing combustion system, efficient heat delivery is achieved
by pre-heating the air with a heat exchanger between the exhaust and incoming air.
Thus, the catalytic heater has the capability of efficiently delivering high grade
heat through the stainless steel cage without using heat exchangers for the inlet
and outlet air flows and pumps. This can be particularly useful in situations, as
earlier mentioned, in catalytically combusting low energy value fuels, small sizes,
or non-flammable fuel-gas mixtures such as tail gas from refineries. The copper or
aluminum block 220 is placed substantially adjacent to a thermal contact with an electrically
insulating but thermally conductive layer of alumina 219 or at coating such as silicon
carbide on copper or anodize coating on the copper or aluminum block 220. The electrically
insulating layer 219 is in thermal contact with a thermopile. The thermopile has junctions
of Bismuth Telluride semiconductors (alternating doping) and metallic conductors between
the heat source and heat sink to create voltage and current from the temperature differences
between the heat source and the heat sink. Electrical connections 211 on the thermopile
deliver electrical power to external applications such as lights, fans, radios, cellular
phones, televisions. A heat pipe 229 is thermally connected to the thermopile through
an electrically insulating layer 219, such as, for example, an alumina sheet, to remove
heat by boiling a working fluid and transferring the heat by condensation to a fined
convective and radiating heat sink 22. The heat sink dissipates heat into a fluid
as the surrounding convective air flow or body of water such as in a hot water tank.
This heat pipe 229 can be embedded into the structure or machine to maintain temperature
in the structure or machine. Within the heat pipe is a wicking material to draw liquid
working fluid such as water, methanol, ammonia, or Freon back to the hot boiling surface
from the condensation cooler areas.
[0068] In Figure 4, condensation 214 of the working fluid is shown condensing as droplets
and with gravity the larger droplets flow down the surface of the condensing surface
to return to a reservoir of working fluid 216. The reservoir of working fluid is then
in contact with the boiling surface and the wick 213 is also used to move liquid fluid
into contact with the boiling surface. The heat flowing from the thermopile boils
the working fluid liquid and then travels as a gas to the condensing surface 214 to
deliver heat to the heat sink 22 when the working fluid condenses from a gas to a
liquid. On the opposite side of the heater, a lower temperature heat removal system
thermally coupled to the exterior of the stainless steel cage. Loops of copper or
stainless steel tubing 223 can be brazed to a stainless steel cage 206 surrounding
the catalytic bed. The working fluid of methanol, methanol and water, ethylene glycol
and water, water, ammonia, hydrogen, or Freon can be pumped around the tubing on the
stainless steel cage of the catalytic bed. When the working fluid boils it can remove
heat at the boiling point of the fluid. If the fluid does not boil it can remove heat
at a range of temperature across the surface of the heater as the working fluid temperature
is raised and the heat added to the fluid. The pump 28 can be used to change the rate
at which the working fluid is circulated. This in turn can deliver heat at different
temperatures. If the pump 28 is stopped or slowed the flow is slowed or blocked and
the heat delivery is slowed or stopped.
[0069] The fluid loops 203 coming from the catalytic bed pass through a finned or non-finned
heat sink 22 outside of the chimney 23 that either condenses working fluid gas or
educes the working fluid temperatures and subsequently delivers heat to the heat sink
22. The heat sink conducts, convects, and radiates heat to the fluids such as air
or water. The heat sink could be imbedded in floors, roads, runways, landing pads,
walk ways, athletic fields, greenhouses, walls, furniture, air flow ducts, apparel,
mirrors, windows, batteries, electronics, machinery, or automobiles,
[0070] In Figure 5, the jet heater is configured to heat fuel cells. In this exemplary embodiment,
a fuel cell is fueled through a fuel delivery membrane 256, either porous or selectively
permeable such as, for example, silicone rubber, that essentially blocks the free
flow of liquid though the fuel cell but delivers a controlled rate of fuel delivery
over the surface of the fuel cell fuel electrode. The fuel cell includes of the fuel
delivery membrane 256, fuel electrode 255, in the form of platinum and ruthenium catalysts
on activated carbon granules and electrolyte such as Nafion membrane 254, air electrode
253 such as platinum catalyst on activated carbon granules. The diffusion fed methanol
fuel cell used in this example has a performance that is 10 to 30 times higher at
65°C then at 20°C. It is also important to maintain an elevated temperature of the
fuel cell during operation to allow product water to vaporize and leave the fuel cell
air electrode 253 at a sufficient rate to avoid product water flooding the air electrode
253 of the fuel cell.
[0071] In the case of an alkaline electrolyte fuel cell, the fuel cell temperature can be
elevated to prevent carbonate formations in the electrolyte. For solid oxide and carbonate
electrolyte fuel cells, one must keep the electrolyte conductivity sufficiently high
to be useable. Because the boiling point of the fuel in this embodiment is used and
the pressure of the fuel can be set, the condensation point and temperature of the
delivered fuel to the fuel cell is set. Other fuels such as methanol and water or
ethanol can be used that have higher boiling points, but the condensation point and
heat delivery can be set by this effect. When the fuel cell temperature goes above
the condensation temperature, the fuel no longer condenses on the membrane and the
liquid fuel can boil in the reservoir and be forced back out through a valve 285 to
the source reservoir 251. In doing this, the fueling rate is decreased but also the
catalytic bed throttles back by not delivering fuel to the porous tubes. The fuel
cell operates on the fuel vapor that comes through the fuel delivery membrane 256.
This may decrease the power output of the fuel cell and dramatically decrease the
heat from the heater and acts like thermostatic heater to the fuel cell. Thus, one
should avoid excessive temperatures on the fuel cell and maintaining an optimum temperature
in the fuel cell. The fuel is delivered to the catalytic bed cavity through at porous
tubes 3 the first is through a capillary tube 6 that delivers liquid fuel to the porous
tube exit. The capillary tube 6 sets the delivery rate of fuel to the heater. When
temperatures in the capillary tube 6 reach the boiling point of the fuel, the fuel
delivery rate will be dramatically decreased when gas instead of liquid is passed
through the capillary tube 6. When the fuel boils and is pressurized in the reservoir,
the fuel level will decrease as fuel is pushed back into the source reservoir 251
and the fuel level in the heat exchange reservoir goes below the capillary tube 6
to the at least two tubes 281. A flow resistance tube 280 acts as fuel vapor vent
to the heat exchange reservoir 284. This allows the heat exchange reservoir 284 to
vent through this flow resistance tube 280 to the atmosphere through the jet cavity
heater and avoid excessive pressurization.
[0072] The vaporization and condensation in the heat exchanger depends on the working fluid
having the atmosphere removed from the loops and the heat exchange reservoir. Thus,
the vent through the capillary tube 280 is needed as a purge route. The fuel vapor
and air that is purged, flows through the porous tubes and is combusted in the catalytic
bed cavity and catalytic bed. The diameter and length of the vapor route and liquid
route tubes can be selected to set the power output rates between cold fueling and
the hot idle rate of the heater due to the contrast in flow rates for the two different
fueling routes at different temperatures. The fuel that flows to the porous tubes
as the portion that reached the jet as liquid travels preferentially through the porous
sides of the porous tube exit. The high temperatures and catalytic properties of the
walls of the porous tubes and inlet lines are high enough such that fuels such as
methanol decompose to a hydrogen rich gas (or plasma) as they flow through the nozzle
into the cavity. This decomposition of fuel further enhances the complete combustion
and catalytic reaction of the fuel and oxygen at the cavity wall. The fuel that flows
to the porous tubes as the portion that reached the jet as vapor more preferentially
enters the cavity through the porous tubes' exit nozzle. The completion of the catalytic
burn occurs in the catalytic bed with low oxygen catalytic combustion as the fuel
diffuses into the inner surface 264 with the in-diffusion of oxygen from the surrounding
air flow in the chimney and is completed with catalytic combustion toward the outside
surface of the catalytic bed in an oxygen rich environment from the outside air. The
temperature gradient in this situation goes from highest in the catalytic bed cavity
or on the inner surface 264 of the catalytic bed to the perimeter of the catalytic
bed, when the stainless steel cage 261 and cooling loops remove heat along with radiant
cooling and convective cooling by the air flow up the chimney.
[0073] Another example of the heater system coupled to a fuel cell is to have a fuel independent
heat pipe 274 thermally connected to the exterior cage 261 of the jet cavity heater.
In this embodiment, the heat pipe could be a heat pipe 291 with a working fluid such
as, for example, Freon, water, ammonia, ethanol, propane, butane, pentane, and methanol.
[0074] Within the heat pipe 291, a wicking material such as woven mesh or fiber glass cloth
is packed up against the heater interior surface of the heat pipe 291. This acts to
wick liquid working fluid to the inner surface of the heat pipe 291. The working fluid
boils, moves through the heat pipe as a vapor, and then condenses on the inner surfaces
of the heat pipe that is in thermal contact with a fuel cell 289. This delivers heat
to the fuel cell. Shown in this illustration the heat pipe 291 is in thermal contact
with the fuel manifold 289 of the heat pipe 291. The condensate liquid working fluid
then flows down the inner condensing surfaces (for example, attracted by gravity)
to return liquid working fluid to the heat pipe reservoir 272. The wicking material
could be extended to the condensation surfaces 268 to be able to wick the liquid working
fluid against gravity, such as when the fuel cell 289 is below the vertical height
of the jet cavity catalytic heater cage contact 262. The fuel cell 289, as an example,
could be a hydrogen fueled fuel cell and the manifold 289 is filled with hydrogen
gas 275 and fibrous matrix or channels 289 that permit thermal conductivity. These
fuel cells 289 could also be electrical conductors making contact with fuel electrode
269 and/or flow routes for the hydrogen gas. It should be mentioned that for hydrogen
fuel cells the vent gas diluted with nitrogen from the fuel cell can be terminated
into the catalytic cavity 290 to safely combust the hydrogen gas, such as shown in
Figure 1 as an inlet tube 37. The hydrogen fuel cell may include of the fuel manifold
289, gas inlet lines 18, platinum coated activated carbon granular fuel electrodes
269, an electrolyte 270 such as hydrogen ion conductive electrolyte such as Nafion
or anion conductive electrolyte such as potassium hydroxide impregnated asbestos mat,
platinum coated activated carbon granular air electrode 271.
[0075] In Figure 6 the electrical output and interface system is shown. The thermopile,
heat to electrical energy converter, and/or fuel cell 300 delivers DC current to charge
a battery or capacitor 302. The direct current output may be moderated or converted
through devices such as a DC to DC converter to match the desired charging voltage
on the battery or capacitor 302. In particular the high current low voltage of the
thermopiles and fuel cells can be converted to high voltage low current through a
switched DC current, a step up transformer, and rectifier. A check diode 301 is placed
in the circuit to prevent back flow of current from the battery or capacitor 302 into
the thermopile or fuel cells 300. An electrical power controller 303 is electrically
connected to the battery 302 to deliver suitable electricity to appliances such as,
for example, light emitting diodes 304, fluorescent lamps, fans, radios 306, televisions,
cellular phones, detectors, telephones, and the like. First switch 307, second switch,
308, and third switch 309 are used to control the various appliances.
[0076] While this invention has been described in conjunction with the specific embodiments
outlined above, it is evident that many alternatives, modifications and variations
will be apparent to those skilled in the art. Accordingly, the preferred embodiments
of the invention as set forth above are intended to be illustrative, not limiting.
Various changes may be made without departing from the scope of the invention.
1. A catalytic heater comprised of:
- one or more fuel reservoirs (30);
- one or more pipes (12, 29, 41) connected to the one or more reservoirs (30);
- one or more porous tubes (3) connected to the one or more pipes (12, 29, 41) and
directed into a cavity (1); and
- the cavity (1) bounded by a porous catalytic wall (2) which is in diffusive contact
with an oxidizer gas to achieve catalytic combustion with fuel from the one or more
porous tubes (3);
wherein oxidation occurs on the porous catalytic wall (2) between oxidizer molecules
diffusing from outside the porous catalytic wall (2) and a plasma within the cavity
(1) diffusing towards the porous catalytic wall (2), wherein the plasma is formed
from vaporized fuel released via the one or more porous tubes (3), such that the oxidation
generates heat.
2. The heater according to claim 1, wherein the fuel is boiling and achieves a state
of auto-thermostatic behavior.
3. The heater according to claim 1, wherein the one or more pipes (12, 29, 41) include
supply fuel tubes (41) having a sufficiently small diameter and long length to restrict
a flow of liquid fuel to the one or more porous tubes (3), and the supply fuel tubes
(41) are in thermal contact with catalytic combustion such that the fuel will vaporize
in the supply fuel tubes (41) and by greater volume effect reduce fuel flow delivery
rate through supply tubes.
4. The heater according to claim 1, wherein the porous catalytic wall (2) is comprised
of a porous matrix of high temperature substrate material and coating of catalytic
material, wherein the porous catalytic wall (2) is contained with a matrix cage.
5. The heater according to claim 4, wherein the matrix cage is a thermal conductor and
may have fluid circulation.
6. The heater according to claim 1, wherein the porous catalytic wall (2) is comprised
of rock wool coated with catalysts selected from the group consisting of platinum,
palladium, rhodium, copper, zinc, nickel, iridium, tin, osmium, ruthenium, silver,
titanium oxide, iron, and transition metals.
7. The heater according to claim 1, further comprising a thermopile (20) or heat-to-electrical-conversion
device in thermal contact with the cavity (1), porous catalytic wall (2), or a combination
thereof.
8. The heater according to claim 1, wherein the fuel is boiling which pressurizes the
fuel and pushes the fuel in a direction away from the one or more porous tubes (3).
9. The heater according to claim 1, wherein the heater combusts gases of hydrogen, carbon
monoxide, methane, butane, propane, methanol, ethanol, ether, ethane, pentane, dimethylether.
10. The heater according to claim 1, wherein the heater combusts vent gasses from fuel
cells, refineries, or processes that generate non-combustible gasses.
11. The heater according to claim 1, further comprised of thermal actuated valves (7,
10, 39) to permit flow or block flow depending on temperature.
12. The heater according to claim 1, wherein the heater delivers electricity to DC-DC
converters, batteries, capacitors, DC-AC converters, voltage regulators, light emitting
diodes, motors, fans, switches, radios, televisions, cellular phones, or a combination
thereof.
13. The heater according to claim 1, further being comprised of a preheating means (340)
adjacent to at least one of the one or more pipes (12).
14. The heater of claim 13, wherein the preheating means (340) includes a fuel restrictor
to limit heat output.
1. Eine katalytische Heizung umfassend:
- ein oder mehrere Brennstoffreservoirs (30);
- eine oder mehrere mit dem einen oder mehreren Brennstoffreservoirs (30) verbundene
Leitungen (12, 29, 41);
- ein oder mehrere mit der einen oder mehreren Leitungen (12, 29, 41) verbundene und
in einen Hohlraum (1) gerichtete poröse Rohre (3); und
- der Hohlraum (1) von einer porösen katalytischen Wand (2) begrenzt wird, welche
in diffusivem Kontakt mit einem Oxidiergas steht, um eine katalytische Verbrennung
mit Brennstoff aus dem einen oder mehreren porösen Rohren (3) zu erzielen,
wobei die Oxidation auf der porösen katalytischen Wand (2) zwischen Oxidatormolekülen,
die von aussen durch die poröse katalytische Wand (2) diffundieren, und einem Plasma
innerhalb des Hohlraums (1), das in Richtung der porösen katalytischen Wand (2) diffundiert,
stattfindet, wobei das Plasma aus verdampften Brennstoff, der durch das eine oder
die mehreren porösen Rohre (3) diffundiert, geformt wird, so dass die Oxidation Hitze
erzeugt.
2. Die Heizung gemäss Anspruch 1, wobei der Brennstoff siedet und einen Zustand von autothermostatischem
Verhalten erreicht.
3. Die Heizung gemäss Anspruch 1, wobei die eine oder mehrere Leitungen (12, 29, 41)
Brennstoffversorgungsrohre (41) mit einem genügend geringen Durchmesser und langer
Länge umfassen, um einen Fluss an flüssigem Brennstoff zu dem einen oder mehreren
porösen Rohren (3) zu beschränken, und wobei die Brennstoffversorgungsrohre (41) in
thermischem Kontakt mit der katalytischen Verbrennung stehen, so dass der Brennstoff
in den Brennstoffversorgungsrohren (41) verdampft wird und durch Wirkung des grösseren
Volumens die Brennstoffzuführrate durch die Versorgungsrohre reduziert wird.
4. Die Heizung gemäss Anspruch 1, wobei die poröse katalytische Wand (2) eine poröse
Matrix aus Hochtemperatursubstratmaterial und eine Beschichtung aus katalytischem
Material enthält, wobei die poröse katalytische Wand (2) in einen Matrixkäfig eingebunden
ist.
5. Die Heizung gemäss Anspruch 4, wobei der Matrixkäfig ein thermischer Leiter ist und
einen Flüssigkeitsumlauf aufweisen kann.
6. Die Heizung gemäss Anspruch 1, wobei die poröse katalytische Wand (2) Steinwolle enthält,
die mit Katalysatoren ausgewählt aus der Gruppe bestehend aus Platin, Palladium, Rhodium,
Kupfer, Zink, Nickel, Iridium, Zinn, Osmium, Ruthenium, Silber, Titanoxid, Eisen und
Übergangsmetallen, beschichtet ist.
7. Die Heizung gemäss Anspruch 1, ferner umfassend eine Thermosäule (20) oder eine Wärme-in-Strom-Umwandlungsvorrichtung
in thermischem Kontakt mit dem Hohlraum (1), der porösen katalytischen Wand (2) oder
einer Kombination davon.
8. Die Heizung gemäss Anspruch 1, wobei der Brennstoff siedet, was den Brennstoff unter
Druck setzt und den Brennstoff in eine Richtung weg von dem einen oder mehreren Rohren
(3) drückt.
9. Die Heizung gemäss Anspruch 1, wobei die Heizung Gase von Wasserstoff, Kohlenstoffmonoxid,
Methan, Butan, Propan, Methanol, Ethanol, Ether, Ethan, Pentan, Dimethylether verbrennt.
10. Die Heizung gemäss Anspruch 1, wobei die Heizung Abgase von Brennstoffzellen, Raffinerien,
oder Prozessen, die nicht brennbare Gase generieren, verbrennt.
11. Die Heizung gemäss Anspruch 1, ferner enthaltend thermisch gesteuerte Ventile (7,
10, 39), um einen Fluss temperaturabhängig zu erlauben oder zu blockieren.
12. Die Heizung gemäss Anspruch 1, wobei die Heizung Elektrizität an Gleichstrom-Gleichstromumwandler,
Batterien, Kondensatoren, Gleichstrom-Wechselstromumwandler, Spannungsregler, Licht
emittierende Dioden, Motoren, Lüfter, Schalter, Radios, Fernseher, Mobiltelefone oder
eine Kombination davon liefert.
13. Die Heizung gemäss Anspruch 1, ferner umfassend ein Vorheizmittel (340) neben wenigstens
einer der einen oder mehreren Leitungen (12).
14. Die Heizung gemäss Anspruch 13, wobei das Vorheizmittel (340) einen Brennstoffbegrenzer
umfasst, um die Wärmeabgabe zu begrenzen.
1. Chauffage catalytique comprenant :
- un ou plusieurs réservoirs de combustible (30) ;
- un ou plusieurs conduits (12, 29, 41) raccordés à l'un ou plusieurs réservoirs (30)
;
- un ou plusieurs tubes poreux (3) raccordés à l'un ou plusieurs conduits (12, 29,
41) et dirigés dans une cavité (1) ; et
- la cavité (1) étant reliée par une paroi catalytique poreuse (2) qui est en contact
par diffusion avec un gaz oxydant permettant d'atteindre une combustion catalytique
avec un combustible provenant de l'un ou plusieurs tubes poreux (3) ;
dans lequel l'oxydation survient sur la paroi catalytique poreuse (2) entre des molécules
d'oxydant se diffusant de l'extérieur de la paroi catalytique poreuse (2) et un plasma
dans la cavité (1) se diffusant vers la paroi catalytique poreuse (2),
dans lequel le plasma est formé à partir de combustible vaporisé libéré via l'un ou
plusieurs tube(s) poreux (3), de sorte que l'oxydation génère de la chaleur.
2. Chauffage selon la revendication 1, dans lequel le combustible bout et atteint un
état de comportement auto-thermostatique.
3. Chauffage selon la revendication 1, dans lequel le un ou plusieurs conduits (12, 29,
41) incluent des tubes de combustible d'alimentation (41) présentant un diamètre suffisamment
petit et une longueur suffisamment longue permettant de limiter un écoulement de combustible
liquide à l'un ou plusieurs des tubes poreux (3) et les tubes de combustible d'alimentation
(41) sont en contact thermique avec la combustion catalytique, de sorte que le combustible
se vaporise dans les tubes de combustible d'alimentation (41) et par un effet de volume
supérieur réduit le débit de distribution de l'écoulement de combustible, à travers
des tubes d'alimentation.
4. Chauffage selon la revendication 1, dans lequel la paroi catalytique poreuse (2) est
composée d'une matrice poreuse d'un matériau de substrat haute température et un revêtement
de matériau catalytique, dans lequel la paroi catalytique poreuse (2) est contenue
avec une cage matrice.
5. Chauffage selon la revendication 4, dans lequel la cage matrice est un conducteur
thermique et peut avoir une circulation de fluide.
6. Chauffage selon la revendication 1, dans lequel la paroi catalytique poreuse (2) est
composée de laine de roche revêtue de catalyseurs sélectionnés dans le groupe constitué
de platine, palladium, rhodium, cuivre, zinc, nickel, iridium, étain, osmium, ruthénium,
argent, oxyde de titane, fer et métaux de transition.
7. Chauffage selon la revendication 1, comprenant en outre une thermopile (20) ou un
dispositif de conversion de chaleur en électricité en contact thermique avec la cavité
(1), la paroi catalytique poreuse (2) ou une combinaison de celles-ci.
8. Chauffage selon la revendication 1, dans lequel le combustible bout, ce qui le pressurise
et le pousse dans une direction s'éloignant de l'un ou plusieurs tubes poreux (3).
9. Chauffage selon la revendication 1, dans lequel le chauffage brûle des gaz d'hydrogène,
monoxyde de carbone, méthane, butane, propane, méthanol, éthanol, éther, éthane, pentane,
diméthyléther.
10. Chauffage selon la revendication 1, dans lequel le chauffage brûle des gaz de purge
provenant des piles à combustibles, des raffineries ou des processus qui génèrent
des gaz non-combustibles.
11. Chauffage selon la revendication 1, comprenant en outre des vannes actionnées thermiquement
(7, 10, 39) afin de permettre l'écoulement ou de bloquer l'écoulement en fonction
de la température.
12. Chauffage selon la revendication 1, dans lequel le chauffage fournit de l'électricité
à des convertisseurs DC-DC, des batteries, des condensateurs, des convertisseurs DC-AC,
des régulateurs de tension, des diodes électroluminescentes, des moteurs, des ventilateurs,
des commutateurs, des radios, des télévisions, des téléphones mobiles ou une combinaison
de ceux-ci.
13. Chauffage selon la revendication 1, étant composé en outre d'un moyen de préchauffage
(340) adjacent à au moins un de l'un ou plusieurs conduits (12).
14. Chauffage selon la revendication 13, dans lequel le moyen de préchauffage (340) inclut
un limiteur de combustible permettant de limiter l'émission de chaleur.